66681400 has 48 divisors (see below), whose sum is σ = 159242040. Its totient is φ = 25948800.

The previous prime is 66681383. The next prime is 66681401. The reversal of 66681400 is 418666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66681401) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2895 + ... + 11905.

Almost surely, 2^66681400 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66681400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (79621020).

66681400 is an abundant number, since it is smaller than the sum of its proper divisors (92560640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66681400 is a wasteful number, since it uses less digits than its factorization.

66681400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9064 (or 9055 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 66681400 is about 8165.8679881566. The cubic root of 66681400 is about 405.5100012078.

It can be divided in two parts, 66681 and 400, that added together give a square (67081 = 259²).

The spelling of 66681400 in words is "sixty-six million, six hundred eighty-one thousand, four hundred".